JP6635158B2 - A mechanism to perform color forced parameter conversion - Google Patents

Description

  A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright holder shall not object to the reproduction of this patent document or the present disclosure by anyone as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyrights.

FIELD OF THE INVENTION The present invention relates to the field of color management, and in particular, to mapping pure input colors to true output colors via color management.

  For commercial and transactional printers, apply Force-Black (K-Force-K) conversion to colors to produce more desirable color output and / or save ink / toner It is common to do. This transformation essentially maps input colors that are close to black to pure black (or grayscale) colors.

  However, it may be desirable to perform X compulsory conversion, assuming that X is a general color parameter. Such parameters include black (eg, traditional K-enforcement); primary colors (eg, process colors, cyan, magenta or yellow); secondary colors (eg, red, green or blue); hue angles (eg, Ricoh red). -Red) hue); Euclidean distance (eg strict color substitution); Rich black (eg X forced but towards rich black); Lightness (eg limiting darkness / brightness); Chroma (eg Limit the chroma to define the maximum gamut); or any set of colors defined through coordinate transformation.

  Therefore, a mechanism for performing X forced conversion is desired.

  In one embodiment, a printing system is disclosed. The printing system performs one or more color caches that store the input colors and corresponding output colors, and an X-force transform that receives the input colors and maps the input colors to the output colors based on predefined color parameters. A color management unit including a color engine (CE) to execute.

  In a further embodiment, a method is disclosed that includes receiving an input color and performing an X coercion that maps the input color to an output color based on a predefined color parameter.

A better understanding of the present invention may be had from the following detailed description, taken in conjunction with the following drawings.
FIG. 2 is a block diagram of one embodiment of a printing system. FIG. 3 is a block diagram of one embodiment of a print controller. FIG. 3 illustrates an embodiment of a color management unit. 5 is a flowchart illustrating one embodiment of a process for performing X coercion. 5 is a flowchart illustrating another embodiment of a process for performing X coercion. FIG. 4 illustrates an embodiment of code implemented to perform X coercion. FIG. 4 illustrates an embodiment of code implemented to perform X coercion. FIG. 4 illustrates an embodiment of code implemented to perform X coercion. FIG. 2 illustrates an embodiment of a computer system.

  A mechanism for executing X forced conversion is described. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but those skilled in the art may practice the present invention without such specific details. That will be clear. On the other hand, well-known structures and devices are shown in block diagram form in order to avoid obscuring the principles underlying the present invention.

  Reference to “an embodiment” or “an embodiment” herein includes a particular feature, structure, or characteristic described in connection with that embodiment in at least one embodiment of the invention. Means that. The appearances of the phrase "in one embodiment" throughout the specification are not necessarily all referring to the same embodiment.

  FIG. 1 is a block diagram illustrating one embodiment of a printing system 130. Host system 110 is in communication with printing system 130 for printing sheet image 120 on a print medium 180 (eg, paper) via a printer. The resulting print media 180 may be printed in color and / or in any of a number of shades of gray, including black and white (eg, cyan, magenta, yellow and black (CMYK)). Host system 110 may include any computing device, such as a personal computer, server, or even a digital imaging device, such as a digital camera or scanner.

  Sheet image 120 may be any file or data that describes how an image should be printed on a sheet of print media 180. For example, sheet image 120 may include PostScript data, Printer Command Language (PCL) data, and / or any other printer language data. Print controller 140 processes the sheet image to generate a bitmap 150 to be transmitted for printing on print media 180 via printer 160. Printing system 130 may be a high-speed printer operable to print relatively large volumes (eg, more than 100 pages per minute). Print medium 180 may be continuous paper, cut sheet paper, and / or any other tangible medium suitable for printing. Printing system 130 includes, in one generalized form, a printer 160 that presents a bitmap 150 to a print medium 180 (eg, via toner, ink, etc.) based on sheet image 120.

  Print controller 140 is any system, apparatus, software, circuit, and / or other suitable component operable to convert sheet image 120 to generate bitmap 150 according to printing on print media 180. Is also good. In this regard, print controller 140 may include processing and data storage functions.

  FIG. 2 is a block diagram illustrating one embodiment of the print controller 140. The print controller 140 (eg, a DFE or digital front end), in its generalized form, includes a color management module 210, an interpreter module 212, and a halftoning module 214. The color management module 210 provides a color mapping from the input color space to the printer 160 color space.

  The interpreter module 212 interprets, renders, rasterizes, or otherwise converts the image of the print job (e.g., a raw sheet side [sheet side] image or printer language data, e.g., the sheet image 120) into a sheet surface. Operable to make a bitmap. The sheet surface bitmap generated by the interpreter module 212 is a two-dimensional array of pixels, each representing an image (eg, a continuous tone image (CTI)) of the print job, and a full sheet surface bitmap. Also called. A two-dimensional pixel array is considered a "full" sheet surface bitmap because such a bitmap contains the entire set of pixels of the image. The interpreter module 212 is operable to interpret or render multiple raw sheet surfaces concurrently, whereby the rate of rendering substantially matches the rate of imaging of the production print engine. Halftoning module 214 is operable to represent the sheet surface bitmap as a halftone pattern of ink. For example, halftoning module 214 may convert the pixels into a halftone pattern of CMYK ink for application to paper.

  In one embodiment, the color management unit 210 performs an ICC-based workflow to execute a color-managed workflow by mapping to determine a CMYK value for each pixel in a particular object to be printed at the printer 160. Use profiles. FIG. 3 is a block diagram illustrating one embodiment of the color management unit 210. The color management unit 210 includes one or more color caches 310 and one or more color look-up tables (LUTs) 320. Color cache 310 may be a hardware and / or software component that stores color mapping data. Thereby, future requests for that data can be serviced faster.

  In one embodiment, upon receiving an input color, color management unit 210 performs a lookup in color cache 310 to determine whether the input color is included in color cache 310 along with a corresponding output color. A color engine (CE) 330 is included. If so, the output color is provided for the color management workflow. However, if there are no entries in the color cache 310, the LUT 320 is used to perform multidimensional interpolation to generate the output color. Next, the input colors and the resulting output colors are stored in color cache 310 as entries for later use.

  The color management unit 210 also performs X compulsory conversion to map input colors to output colors based on general predefined color parameters ("X"). For example, X may represent a K-force parameter where the input color is mapped to a pure black (or grayscale) color. However, in another embodiment, X may represent a primary color (eg, primary color (CMY) coercion), in which case the input color is mapped to the primary color.

  In still other embodiments, X is a secondary color parameter (eg, secondary color enforcement (red, green or blue (RGB)), a hue angle (preserve hue, Euclidean distance to perform strict color substitution, rich Any set of colors defined through black to K, K to rich black, brightness to limit darkness / brightness, chroma to limit chroma to define the maximum gamut, or chroma or coordinate transformation May be represented.

  According to an embodiment, the management unit 210 dynamically identifies the X forced input color to perform the conversion. In such an embodiment, color engine 330 allows two colors to be interpolated in LUT 320 simultaneously. In this manner, LUT 320 enables X-forced implementation by mapping an input color to two output colors and general forcing parameters. LUE 320 performs the following:

InColor → {OutColor1, x, OutColor2} where
InColor = input color to be color managed;
OutColor1 = output color when X is not enforced;
x = parameter (eg, 0 to n) that is compared to the enforced threshold when determining whether X is enforced;
OutColor2 = Output color when X is forced.

  Based on the above, one interpolation gives {OutColor1, x, OutColor2} and the final color managed output color is calculated by:

_{if (x <x Threshold) →} OutColor = OutColor1
else OutColor = CoutColor2 where
x _Threshold = current enforced threshold;
OutColor = final color managed output color.

  FIG. 4 is a flowchart illustrating one embodiment for performing the X enforcement process. At processing block 410, an input color (InColor) is received at color management unit 210. At decision block 420, a determination is made as to whether the InColor is in the color cache 310. If so, at processing block 430, the output color corresponding to InColor is retrieved from color cache 310. At processing block 440, the output color is returned.

  If it is determined at decision block 420 that the InColor is not in cache 310, then at processing block 450 interpolation is performed at LUT 320 as discussed above. In a further embodiment, LUT 320 performs a complete n to 9 dimensional interpolation to calculate a first output color (OutColor1), a second output color (OutColor2), and a forcing parameter x. Here, the output space is CMYK.

At decision block 460, a determination is made as to whether x <x _Threshold . In some embodiments, the enforcement parameter x is selected by the color management unit 210 and may be any parameter that is consistent with LUT generation. If x ≧ x _Threshold , the processing block 470 sets the output color (OutColor) to OutColor1. In embodiments, the enforcement parameter x and the predefined color parameter X may be received from a user (or operator) via a user interface (eg, a graphical user interface (GUI)). In other embodiments, the x _Threshold may be selected by the color management unit 210 or by an operator via a GUI.

At processing block 480, the InColor and OutColor are stored in the cache 310. According to some embodiments, cache 310 may need to be reset if x _Threshold changes. In such embodiments, cache 310 is cleared and new colors are cached during the X enforcement process based on the updated x _Threshold . However, in other embodiments, if x _Threshold changes dynamically (or frequently), then InColor, x, OutColor1, and OutColor2 may all be cached. At processing block 440, the output color is returned.

If it is determined at decision block 460 that x <x _Threshold , then at processing block 490 OutColor is set to OutColor2. Thereafter, the InColor and OutColor are stored in cache 310 (processing block 480) and the OutColor is returned (processing block 440).

As discussed above, in embodiments where the x _Threshold changes dynamically and / or frequently, it may be advantageous for cache 310 to store InColor, x, OutColor1, and OutColor2. FIG. 5 is a flowchart illustrating one embodiment for performing the X enforcement process in embodiments where the x _Threshold changes dynamically.

  At processing block 510, the InColor is received at the color management unit 210. At decision block 520, a determination is made as to whether the InColor is in the color cache 310. If not, at processing block 530, interpolation is performed in LUT 320 to calculate OutColor1, OutColor2 and parameter x. At processing block 540, InColor, OutColor1, OutColor2, and x are stored in cache 310.

At decision block 550, a determination is made as to whether x <x _Threshold . If x ≧ x _Threshold , at processing block 560, OutColor is set to OutColor1. At processing block 570, OutColor is returned. If it is determined at decision block 550 that x <x _Threshold , then at processing block 580 OutColor is set to OutColor2. Thereafter, processing block 570 returns OutColor.

If it is determined at decision block 520 that InColor is in color cache 310, OutColor 1, OutColor2 and x are retrieved from color cache 310 at processing block 525. Thereafter, control proceeds to decision block 550, where a determination is made as to whether x < _xThreshold . Thereafter, OutColor is set and returned to either OutColor1 or OutColor2 as discussed above.

In an alternative embodiment, multiple LUTs can be used to perform the X enforcement process. In such an embodiment, a first LUT (LUT _x ) is implemented to perform a first interpolation that maps InColor to x. In this embodiment, the first interpolation includes an offset to the base node and the stored node weight. Thereafter, x is compared to x _Threshold . In a further embodiment, a second interpolation occurs in the second LUT (LUT ₁ ) upon determining x ≧ x _Threshold . As a result, the output color (OutColor) is set to OutColor1. However, when the determination that x <x _Threshold, the second interpolation occurred in the third LUT (LUT _2), as a result, the output color (OutColor) is set to OutColor2.

In this embodiment, the same amount of memory is used for three LUTs and two interpolations. Thus, if the node spacing is the same and the offset to the base node and the node weight are stored, the additional computation required by this embodiment is negligible. Further, this embodiment provides the benefits of multiple different X-forced LUTs without having a common LUT copy from InColor to OutColor1. Thus, for a given color space, LUT ₁ maps the InColor as "default" LUT to OutColor1, additional X forced LUT is simply (from InColor X) LUTx and LUT ₂ of (OutColor2 from InColor) It may be added by creating pairs. An example may be from RGB to CMYK, where K forcing and K preservation can be implemented on a trivial.

  The above transformation provides a fast and efficient color calculation where only one cache check, one interpolation and one scalar comparison is required. This process leaves the LUT to perform the X coercion. Thus, for the most efficient performance, each of the OutColor1, x and OutColor2 components of LUT 320 should be smooth. Further, x is a scalar and should be relatively simple to calculate. However, other embodiments may handle x with multiple components. Furthermore, the number of LUT nodes should be kept small. Finally, some embodiments may handle multiple xs enforced in the same LUT. However, care should be taken to ensure that the forced regions do not overlap, and a hierarchy may need to be set.

  6A-6C illustrate another embodiment of code implemented to perform X coercion. FIG. 6A shows one embodiment of code implemented to implement X coercion that coerces RGB colors (0,255,100) to CMYK colors (128,128,0,2), and shows typical color substitutions that may be desired. Is shown. As shown in FIG. 6A, codes for LUT construction, LUT interpolation and color conversion are included.

  FIG. 6B illustrates one embodiment of code that performs LUT construction for an X enforcement implementation to perform traditional K enforcement for RGB to CMYK, and FIG. 6C illustrates an embodiment for RGB to CMYK. 5 illustrates one embodiment of code for performing LUT construction for an X-forced implementation to force a 354 ° hue angle. The codes for LUT interpolation and color conversion in both embodiments are the same as shown in the embodiment of FIG. 6A.

  FIG. 7 illustrates a computer system 900 in which the printing system 130 and / or the print controller 140 may be implemented. Computer system 900 includes a system bus 920 for communicating information, and a processor 910 coupled with bus 920 for processing information.

  Computer system 900 further includes a random access memory (RAM) or other dynamic storage 925 (main memory in this case) coupled to bus 920 for storing information and instructions to be executed by processor 910. ). Main memory 925 may also be used to store temporary variables or other intermediate information during the execution of instructions by processor 910. Computer system 900 also includes a read-only memory (ROM) and / or other static storage device 926 coupled to bus 920 for storing static information and instructions used by processor 910. Is also good.

  A data storage device 927, such as a magnetic or optical disk and its corresponding drive, may also be coupled to computer system 900 for storing information and instructions. Computer system 900 may also be coupled to a second I / O bus 950 via an I / O interface 930. A plurality of I / O devices, including a display 924 and input devices (eg, alphanumeric input device 923 and / or cursor control device 922) may be coupled to I / O bus 950. The communication device 921 is for accessing another computer (server or client). The communication device 921 includes a modem, a network interface card or other well-known interface device, such as one used for coupling to an Ethernet, token ring, or other type of network. You may.

  Embodiments of the present invention may include various steps as described above. These steps may be embodied in machine-executable instructions. The instructions can be used to cause a general-purpose or special-purpose processor to perform certain steps. Alternatively, these steps may be performed by specific hardware components, including fixed configuration logic to perform those steps, or by any combination of programmed computer components and custom hardware components. May be executed.

  The elements of the present invention may be provided as a machine-readable medium for storing machine-executable instructions. Machine-readable media may be floppy diskettes, optical disks, CD-ROMs and magneto-optical disks, ROM, RAM, EPROM, EEPROM, magnetic or optical cards, propagation media or other types of media / machine-readable media and It may include, but is not limited to, those suitable for storing instructions. For example, the invention may be transferred over a communication link (eg, a modem or network connection) from a remote computer (eg, a server) to a requesting computer (eg, a client) via a data signal embodied in a carrier wave or other propagation medium. May be downloaded as a computer program.

After reading the above description, many variations and modifications of the present invention will no doubt become apparent to those skilled in the art, but are intended to limit any particular embodiment shown and described by way of illustration. It is not intended to be considered. Therefore, references to details of various embodiments are not intended to limit the scope of the claims. The claims themselves describe only those features which are considered essential to the invention.
Some embodiments are described.
[Aspect 1]
A printing system having a color management unit, wherein the color management unit comprises:
A color cache for storing input colors and corresponding output colors;
A color engine (CE) that receives an input color and performs an X coercion that maps the input color to an output color based on predefined color parameters;
The predefined color parameter is selected from a plurality of color parameters,
Printing system.
[Aspect 2]
The printing system of claim 1, further comprising a look-up table (LUT) for generating an output color corresponding to the input color received at the color management unit.
[Aspect 3]
The printing system according to aspect 2, wherein the LUT generates a first output color, a second output color, and a forcing parameter corresponding to the predefined color parameter based on a received input color.
[Aspect 4]
The printing system of aspect 3, wherein the forcing parameter is compared to a forcing threshold to determine which of the first or second output color is generated as the output color.
[Aspect 5]
The printing system according to aspect 4, wherein upon determining that the forcing parameter is smaller than the forcing threshold, the first output color is generated as the output color.
[Aspect 6]
The printing system according to aspect 4, wherein upon determining that the forcing parameter is greater than the forcing threshold, the second output color is generated as the output color.
[Aspect 7]
The printing system according to aspect 3, wherein the color cache stores the first output color, the second output color, and the forcing parameter generated by the LUT.
[Aspect 8]
The printing system of claim 1, wherein the predefined color parameters include a K-force parameter where the input color is mapped to pure black.
[Aspect 9]
Aspect 1 wherein the predefined color parameters include at least one of: a primary color compulsory parameter, a secondary color compulsory parameter, a hue angle compulsory parameter, a rich black compulsory parameter, a lightness compulsory parameter, and a chroma compulsory parameter. Printing system.
[Aspect 10]
A first look-up table (LUT) for generating a forcing parameter based on a received input color, wherein the forcing parameter is generated such that either a first output color or a second output color is generated as an output color. A first LUT, which is compared to a mandatory threshold to determine
A second LUT that generates the first output color as the output color when it is determined that the forcing parameter is less than the forcing threshold;
Upon determining that the forcing parameter is equal to or greater than the forcing threshold, further comprising a third LUT that generates the second output color as the output color.
The printing system according to aspect 1.
[Aspect 11]
A machine-readable medium containing data, wherein said data, when accessed by a processor, includes:
Receive input color;
Performing X forced conversion of mapping the input color to the output color based on a predefined color parameter,
The predefined color parameter is selected from a plurality of color parameters,
Machine readable medium.
[Aspect 12]
Performing the X coercion may include:
Generating a first output color based on the received input color;
Generating a second output color based on the received input color;
Generating a forcing parameter corresponding to the predefined color parameter based on the received input color.
A machine-readable medium according to aspect 11.
[Aspect 13]
When accessed by the processor, the processor further comprises: forcing the forcing parameter with a forcing threshold to determine whether the first output color or the second output color is generated as the output color. 13. The machine-readable medium of aspect 12, including data to be compared.
[Aspect 14]
14. The machine of aspect 13, further comprising data that, when accessed by the processor, causes the processor to generate the first output color as the output color upon determining that the forcing parameter is less than the forcing threshold. Readable medium.
[Aspect 15]
Aspect 14. The machine of aspect 14, further comprising data that, when accessed by the processor, causes the processor to generate the second output color as the output color upon determining that the forcing parameter is greater than the forcing threshold. Readable medium.
[Aspect 16]
15. The machine of aspect 14, wherein the machine further comprises data that, when accessed by the processor, causes the processor to store the input color, the first output color, the second output color, and the forcing parameter in a color cache. Readable medium.
[Aspect 17]
When accessed by the processor, the processor further comprises:
Receiving a second input color;
Determining whether the second input color is stored in the color cache;
When determining that the second input color is stored in the color cache, the data includes data for executing the retrieval of a third output color, a fourth output color, and a second forcing parameter from the color cache. ,
A machine-readable medium according to aspect 16.
[Aspect 18]
When accessed by the processor, the processor may further include the second forcing parameter to determine whether the third output color or the fourth output color is generated as the output color. 18. The machine-readable medium of aspect 17, including data to be compared to the enforced threshold.
[Aspect 19]
When accessed by the processor, the processor further determines that the second input color is not stored in the color cache, the third output color from the color cache, the fourth output color, Aspect 19. The machine-readable medium of aspect 18, comprising data for generating an output color and the second forcing parameter.
[Aspect 20]
When accessed by the processor, the processor further comprises:
Determining whether the first input color is stored in a color cache;
Upon determining that the input color is stored in the color cache, including data for executing the extraction of the first output color, the second output color, and the forcing parameter from the color cache,
A machine-readable medium according to aspect 11.

110 Host System 120 Sheet Image 130 CMYK Printing System 140 Print Controller 150 Bitmap 160 Printer 180 Print Medium

210 Color management module 212 Interpreter module 214 Halftoning module

310 color cache 320 LUT
330 CE

Claims (17)

A printing system having a color management unit, wherein the color management unit comprises:
A color cache for storing input colors and corresponding output colors;
A color engine (CE) that receives an input color and performs an X coercion that maps the input color to an output color based on predefined color parameters;
The predefined color parameter is selected from a plurality of color parameters ,
The printing system is further have a lookup table (LUT) for generating an output color corresponding to the input color, which is received at the color management unit,
The LUT generates a first output color, a second output color and a forcing parameter corresponding to the predefined color parameter based on the received input color,
Printing system. Wherein said either one of the output color or the second output color is to determine is generated as the output color, the forced parameter is compared with the forced threshold claim 1 printing system according. The printing system according to claim 2 , wherein when determining that the forcing parameter is smaller than the forcing threshold, the first output color is generated as the output color. The printing system according to claim 2 , wherein the second output color is generated as the output color when it is determined that the forcing parameter is larger than the forcing threshold. The color cache, the generated by LUT, the first output color, and stores the second said force parameter and the output color of Claim 1 printing system according.   The printing system of claim 1, wherein the predefined color parameters include a K-force parameter where the input color is mapped to pure black.   2. The predefined color parameter comprises at least one of: a primary color compulsory parameter, a secondary color compulsory parameter, a hue angle compulsory parameter, a rich black compulsory parameter, a lightness compulsory parameter, and a chroma compulsory parameter. The printing system as described. A printing system having a color management unit, wherein the color management unit comprises:
A color cache for storing input colors and corresponding output colors;
A color engine (CE) that receives an input color and performs an X coercion that maps the input color to an output color based on predefined color parameters;
The predefined color parameter is selected from a plurality of color parameters,
The printing system is
A first look-up table (LUT) for generating a forcing parameter based on a received input color, wherein the forcing parameter is generated such that either a first output color or a second output color is generated as an output color. A first LUT, which is compared to a mandatory threshold to determine
A second LUT that generates the first output color as the output color when it is determined that the forcing parameter is less than the forcing threshold;
Upon determining that the forcing parameter is equal to or greater than the forcing threshold, further comprising a third LUT that generates the second output color as the output color.
Printing system. A machine-readable medium containing data, wherein said data, when accessed by a processor, includes:
Receive input color;
Performing X forced conversion of mapping the input color to the output color based on a predefined color parameter,
The predefined color parameter is selected from a plurality of color parameters ,
Performing the X coercion may include:
Generating a first output color based on the received input color;
Generating a second output color based on the received input color;
Generating a forcing parameter corresponding to the predefined color parameter based on the received input color.
The machine-readable media. When accessed by the processor, the processor further comprises: forcing the forcing parameter with a forcing threshold to determine whether the first output color or the second output color is generated as the output color. The machine-readable medium of claim 9 , including data to be compared. The method of claim 10 , further comprising: when accessed by the processor, the processor further including data for generating the first output color as the output color when determining that the forcing parameter is less than the forcing threshold. Machine readable medium. The method of claim 11 , further comprising: when accessed by the processor, the processor further comprising, when determining that the forcing parameter is greater than the forcing threshold, generating the second output color as the output color. Machine readable medium. The method of claim 11 , further comprising: when accessed by the processor, the processor causing the input color, the first output color, the second output color, and the forcing parameter to be stored in a color cache. Machine readable medium. When accessed by the processor, the processor further comprises:
Receiving a second input color;
Determining whether the second input color is stored in the color cache;
When determining that the second input color is stored in the color cache, the data includes data for executing the retrieval of a third output color, a fourth output color, and a second forcing parameter from the color cache. ,
14. The machine readable medium of claim 13 . When accessed by the processor, the processor may further include the second forcing parameter to determine whether the third output color or the fourth output color is generated as the output color. The machine-readable medium of claim 14 , including data to be compared to the enforced threshold. When accessed by the processor, the processor may further determine that the second input color is not stored in the color cache, the third output color from the color cache, the fourth The machine-readable medium of claim 15 , including data for generating an output color and the second forcing parameter. When accessed by the processor, the processor further comprises:
Determining whether the entering force colors stored in the color cache;
Upon determining that the input color is stored in the color cache, including data for executing the extraction of the first output color, the second output color, and the forcing parameter from the color cache,
A machine-readable medium according to claim 9 .

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